A critical part of the James Web Space Telescope has already failed according to sources. NASA won't make the announcement yet, but once it reaches the L2 region in about 29 days shit will hit the fan fast and they won't have any choice.

It is unknown why the part failed but, and I'm quoting here:

>At 1:32 UTC it was found that the main controller was somehow disconnected from the fine adjustment thrusters, meaning the telescope will never be able to adjust itself once in place and won't be able to serve its purpose. The last automated check was around 1:22 UTC and the main computer didn't show any anomalies. We are trying to determine if the controller was physically unplugged from the beginning, but it doesn't make sense because of the level of redundancy involved.

TL;DR: Something just disconnected the entire JWST fine tuning thrusters, including redundant cables and controllers, rendering the entire mission useless.